Hard Chrome Plating

We offer
a hard chrome plating service using Chromic Acid - Chromium
Trioxide Flake from Elementis. Our solution is made up of 250g/l
CrO3 and Sulphuric Acid at a 100-1 ratio.

Background: Hard
chrome plating, sometimes referred to as functional chrome
plating, can be applied in thick layers for heavy industrial
applications. It increases wear and corrosion resistance whilst
creating a low co-efficient of friction. With abrasion being
the most common and destructive wear process found in industry,
hard chrome has the potential to solve many problems in pumps,
valves, bearings, etc. throughout a wide range of industries;
including pharmaceutical, chemical, oil and gas, textiles,
printing, food, mining, and countless others.

One application for hard chrome is the refurbishment of worn
components where the metal has been lost through wear or been
manufactured under size, or, even where there has been an excessive
distortion during the hardening process. This application usually
requires a thicker deposit and components are pre-chrome ground
then a suitable deposit of hard chrome is applied before they
are ground back to original sizes and tolerances.

Process: Hard
Chrome plating is an electrolytic process utilising a chromic
acid-based
electrolyte. The component requiring plating becomes
the cathode and, with the passage of a DC current via anodes,
chromium metal builds on the component surface.

Applications: Hard
Chrome plating has many typical applications, some of which
are detailed below:

Thickness: Coatings
can be applied to customer specification and requirements.
For heavier deposits i.e. approx. 0.5mm, it is advisable, if
possible, to capture the ends of the component being
plated to reduce the chance of “chipping” of edge
build up.

Coating thickness is directly proportional to the
parameters dictated by amount of time a component is required
to be in the tank and the calculated running current (normally
2amps per square inch).

Hardness: Hardness
is 950 - 1150HV.

Materials: Most
materials can be Hard Chrome plated, including:

Steel

Stainless
Steel

Cast Iron

Copper

Brass

Bronze Alloys

Nickel Alloys

Plating
Vats: We have the capacity to chrome up to 3.6metres
in length and if you think you may have a possible application
for a component not listed, please contact us to discuss
this further.

Etching: Etching
is carried in accordance with the guidance relevant to the
base material being plated. All components are etched before
Hard Chrome plating to provide a good key for the hard chrome
deposit to be applied.

Jigging: Careful
jigging is required for hard chrome plating, taking into consideration
current carrying capacity and weight of component. Special
attention is necessary for the plating of internal surfaces.
One of the characteristics of hard chrome is its poor throwing
power, therefore auxiliary anodes maybe required at strategic
locations.

Jigging: For
high tensile steels (above 1000N/mm2), there can be a need
for a post-plating heat treatment to eliminate the effect of
hydrogen embrittlement which may occur during the plating process.